Something went wrong. Try again.
(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
Something went wrong. Try again.
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288// SPDX-License-Identifier: GPL-2.0-only/* * Copyright (C) 2006-2009 Red Hat, Inc. * * This file is released under the LGPL. */
#include <linux/kernel.h>#include <linux/module.h>#include <linux/slab.h>#include <net/sock.h>#include <linux/workqueue.h>#include <linux/connector.h>#include <linux/device-mapper.h>#include <linux/dm-log-userspace.h>
#include "dm-log-userspace-transfer.h"
static uint32_t dm_ulog_seq;
/* * Netlink/Connector is an unreliable protocol. How long should * we wait for a response before assuming it was lost and retrying? * (If we do receive a response after this time, it will be discarded * and the response to the resent request will be waited for. */#define DM_ULOG_RETRY_TIMEOUT (15 * HZ)
/* * Pre-allocated space for speed */#define DM_ULOG_PREALLOCED_SIZE 512static struct cn_msg *prealloced_cn_msg;static struct dm_ulog_request *prealloced_ulog_tfr;
static struct cb_id ulog_cn_id = { .idx = CN_IDX_DM, .val = CN_VAL_DM_USERSPACE_LOG};
static DEFINE_MUTEX(dm_ulog_lock);
struct receiving_pkg { struct list_head list; struct completion complete;
uint32_t seq;
int error; size_t *data_size; char *data;};
static DEFINE_SPINLOCK(receiving_list_lock);static struct list_head receiving_list;
static int dm_ulog_sendto_server(struct dm_ulog_request *tfr){ int r; struct cn_msg *msg = prealloced_cn_msg;
memset(msg, 0, sizeof(struct cn_msg));
msg->id.idx = ulog_cn_id.idx; msg->id.val = ulog_cn_id.val; msg->ack = 0; msg->seq = tfr->seq; msg->len = sizeof(struct dm_ulog_request) + tfr->data_size;
r = cn_netlink_send(msg, 0, 0, gfp_any());
return r;}
/* * Parameters for this function can be either msg or tfr, but not * both. This function fills in the reply for a waiting request. * If just msg is given, then the reply is simply an ACK from userspace * that the request was received. * * Returns: 0 on success, -ENOENT on failure */static int fill_pkg(struct cn_msg *msg, struct dm_ulog_request *tfr){ uint32_t rtn_seq = (msg) ? msg->seq : (tfr) ? tfr->seq : 0; struct receiving_pkg *pkg;
/* * The 'receiving_pkg' entries in this list are statically * allocated on the stack in 'dm_consult_userspace'. * Each process that is waiting for a reply from the user * space server will have an entry in this list. * * We are safe to do it this way because the stack space * is unique to each process, but still addressable by * other processes. */ list_for_each_entry(pkg, &receiving_list, list) { if (rtn_seq != pkg->seq) continue;
if (msg) { pkg->error = -msg->ack; /* * If we are trying again, we will need to know our * storage capacity. Otherwise, along with the * error code, we make explicit that we have no data. */ if (pkg->error != -EAGAIN) *(pkg->data_size) = 0; } else if (tfr->data_size > *(pkg->data_size)) { DMERR("Insufficient space to receive package [%u] (%u vs %zu)", tfr->request_type, tfr->data_size, *(pkg->data_size));
*(pkg->data_size) = 0; pkg->error = -ENOSPC; } else { pkg->error = tfr->error; memcpy(pkg->data, tfr->data, tfr->data_size); *(pkg->data_size) = tfr->data_size; } complete(&pkg->complete); return 0; }
return -ENOENT;}
/* * This is the connector callback that delivers data * that was sent from userspace. */static void cn_ulog_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp){ struct dm_ulog_request *tfr = (struct dm_ulog_request *)(msg + 1);
if (!capable(CAP_SYS_ADMIN)) return;
spin_lock(&receiving_list_lock); if (msg->len == 0) fill_pkg(msg, NULL); else if (msg->len < sizeof(*tfr)) DMERR("Incomplete message received (expected %u, got %u): [%u]", (unsigned int)sizeof(*tfr), msg->len, msg->seq); else fill_pkg(NULL, tfr); spin_unlock(&receiving_list_lock);}
/** * dm_consult_userspace * @uuid: log's universal unique identifier (must be DM_UUID_LEN in size) * @luid: log's local unique identifier * @request_type: found in include/linux/dm-log-userspace.h * @data: data to tx to the server * @data_size: size of data in bytes * @rdata: place to put return data from server * @rdata_size: value-result (amount of space given/amount of space used) * * rdata_size is undefined on failure. * * Memory used to communicate with userspace is zero'ed * before populating to ensure that no unwanted bits leak * from kernel space to user-space. All userspace log communications * between kernel and user space go through this function. * * Returns: 0 on success, -EXXX on failure **/int dm_consult_userspace(const char *uuid, uint64_t luid, int request_type, char *data, size_t data_size, char *rdata, size_t *rdata_size){ int r = 0; unsigned long tmo; size_t dummy = 0; int overhead_size = sizeof(struct dm_ulog_request) + sizeof(struct cn_msg); struct dm_ulog_request *tfr = prealloced_ulog_tfr; struct receiving_pkg pkg;
/* * Given the space needed to hold the 'struct cn_msg' and * 'struct dm_ulog_request' - do we have enough payload * space remaining? */ if (data_size > (DM_ULOG_PREALLOCED_SIZE - overhead_size)) { DMINFO("Size of tfr exceeds preallocated size"); return -EINVAL; }
if (!rdata_size) rdata_size = &dummy;resend: /* * We serialize the sending of requests so we can * use the preallocated space. */ mutex_lock(&dm_ulog_lock);
memset(tfr, 0, DM_ULOG_PREALLOCED_SIZE - sizeof(struct cn_msg)); memcpy(tfr->uuid, uuid, DM_UUID_LEN); tfr->version = DM_ULOG_REQUEST_VERSION; tfr->luid = luid; tfr->seq = dm_ulog_seq++;
/* * Must be valid request type (all other bits set to * zero). This reserves other bits for possible future * use. */ tfr->request_type = request_type & DM_ULOG_REQUEST_MASK;
tfr->data_size = data_size; if (data && data_size) memcpy(tfr->data, data, data_size);
memset(&pkg, 0, sizeof(pkg)); init_completion(&pkg.complete); pkg.seq = tfr->seq; pkg.data_size = rdata_size; pkg.data = rdata; spin_lock(&receiving_list_lock); list_add(&(pkg.list), &receiving_list); spin_unlock(&receiving_list_lock);
r = dm_ulog_sendto_server(tfr);
mutex_unlock(&dm_ulog_lock);
if (r) { DMERR("Unable to send log request [%u] to userspace: %d", request_type, r); spin_lock(&receiving_list_lock); list_del_init(&(pkg.list)); spin_unlock(&receiving_list_lock);
goto out; }
tmo = wait_for_completion_timeout(&(pkg.complete), DM_ULOG_RETRY_TIMEOUT); spin_lock(&receiving_list_lock); list_del_init(&(pkg.list)); spin_unlock(&receiving_list_lock); if (!tmo) { DMWARN("[%s] Request timed out: [%u/%u] - retrying", (strlen(uuid) > 8) ? (uuid + (strlen(uuid) - 8)) : (uuid), request_type, pkg.seq); goto resend; }
r = pkg.error; if (r == -EAGAIN) goto resend;
out: return r;}
int dm_ulog_tfr_init(void){ int r; void *prealloced;
INIT_LIST_HEAD(&receiving_list);
prealloced = kmalloc(DM_ULOG_PREALLOCED_SIZE, GFP_KERNEL); if (!prealloced) return -ENOMEM;
prealloced_cn_msg = prealloced; prealloced_ulog_tfr = prealloced + sizeof(struct cn_msg);
r = cn_add_callback(&ulog_cn_id, "dmlogusr", cn_ulog_callback); if (r) { kfree(prealloced_cn_msg); return r; }
return 0;}
void dm_ulog_tfr_exit(void){ cn_del_callback(&ulog_cn_id); kfree(prealloced_cn_msg);}